As a fan of Godzilla but not a big anime fan, I found it dull. It feels like a generic sci-fi anime story that they painted over with Godzilla movie references and nostalgia. Most of it is pseudo-science mumbo-jumbo exposition and a good portion of what's left after that is really annoying anime stereotypes (jumping, yelling little old man; annoying sidekick character-- this time an AI-- with a kid voice; super-genius character who is also inexplicably stupid and ditzy half the time).
I do like the monster designs, and the idea itself could be cool as a monster movie. It's bad in the way of the '98 Godzilla rather than in the way of the other Netflix anime series.
And some of the nostalgia was fun... even if kind of weak.
But over all, it's a snooze.